Sinovac Biotech Ltd. announced that it received prequalification from the World Health Organization (WHO) for its live attenuated varicella vaccine on November 3, 2022. This marks the first WHO prequalified Chinese varicella vaccine and the fourth SINOVAC vaccine to receive WHO approval. The varicella vaccine is derived from the Oka strain and propagated in SINOVAC's proprietary Human Diploid Cell (SV-1 strain), which is made by culturing and harvesting the virus, adding stabilizers and freeze-drying.

According to a phase III efficacy study, the seroconversion rate of the vaccinated children group, ages 1 to 12 years old, was 97.1%; the efficacy of the vaccine was 87.1% against varicella and 89.2% for breakthrough varicella. The vaccine provides 100% protection against moderate and severe cases.